In this April 8, 2008 file photo released by the Iranian President's Office, Iranian President Mahmoud Ahmadinejad, front center, visits the Natanz Uranium Enrichment Facility some 200 miles (322 kilometers) south of the capital Tehran, Iran. Technicians upgrading Iran’s main uranium enrichment facility have tripled partial or full installations of high-tech machines that could be used in a nuclear weapons program to more than 600 since starting their work three months ago, according to diplomats who demanded anonymity because they said they are not authorized to disclose the information, Wednesday April 17, 2013. (AP Photo/Iranian President's Office, file)

VIENNA (AP) — Technicians upgrading Iran’s main uranium enrichment facility have tripled their installations of high-tech machines that could be used in a nuclear weapons program to more than 600 in the last three months, diplomats said Wednesday.

They say the machines are not yet producing enriched uranium and some may be only partially installed. Still the move is the latest sign that 10 years of diplomatic efforts have failed to persuade Tehran to curb its uranium enrichment. Instead, Iran continues to increase its capacities.

The installations also suggest that Iran possesses both the technology to mass-produce centrifuges that can enrich much faster than its present machines and the ability to evade international sanctions meant to keep it from getting materials it needs to do so.

The Islamic Republic insists it has no interest in nuclear weapons and says it’s enriching uranium only for nuclear power and other non-military applications. Iran also asserts it has a right to do so under international law.

But the United States, Israel, and their allies fear Iran may use the technology to create weapons-level uranium that can be used in an atomic bomb. They base their concerns on Tehran’s nuclear secrecy and suspicions they share with the International Atomic Energy Agency that Iran may have worked secretly on nuclear arms.

Experts for years have suggested that the U.N. embargoes against Tehran for defying Security Council demands that it stop enrichment has left Tehran short of high-quality steel, carbon fiber and other materials needed to establish a production line of advanced centrifuges.

But the installations that began early this year and recent Iranian comments indicate the expansion has just begun.

An IAEA report in February said agency inspectors counted 180 of the advanced IR-2m centrifuges at Natanz, Tehran’s main enrichment site, less than a month after Iran’s Jan. 23 announcement that it would start mounting them. The report said it was unclear whether the machines were partly or completely installed.

Two diplomats who spoke to The Associated Press said while IAEA experts visiting the Iranian sites were now able to count more of the centrifuges, they remained uncertain about their operating ability because they were not permitted to get a close enough look.

One of the diplomats who spoke comes from a country critical of Iran’s nuclear program while the other is considered neutral, and both spend much of their time probing Iran’s nuclear activities. They demanded anonymity because they were not authorized to discuss confidential information about IAEA inspections.

A phone call for reaction to Ali Asghar Soltanieh, Iran’s chief IAEA representative, was not returned. The IAEA said it would not comment on the diplomats’ report.

The February IAEA report also said the number of other advanced centrifuge models being tested at an R&D site at Natanz separate from its enrichment plant had substantially increased to more than 300 as of February.

Iranian nuclear chief Fereidoun Abbasi was quoted Sunday by the semiofficial Fars news agency as saying that more than 3,000 high-tech centrifuges have already been produced and will soon phase out the more than 12,000 older-generation enriching machines at Natanz.

If accurate, those numbers show that Iran has managed to outperform expectations published just two years ago. Back then David Albright of the Washington-based Institute for Science and International Security cited unnamed U.S. government sources estimating that raw-material shortages would likely limit production of the advanced machines to no more than 1,000.

Albright on Wednesday said Iran’s apparent ability to mass-produce the machines reflects its success in evading sanctions.

“At this point you have to concede that Iran probably has the material to make up to 3,000 IR2-ms,” he said.

Albright, who occasionally briefs U.S. government officials on Iran’s nuclear program, said much of the material appears to be coming through China from European and Japanese manufacturers. He cited non-U.S. Western government sources for his information but said he could not divulge precise nationalities.

At the present installation rate of about 200 a month, it would take 15 months from the startup date to install the 3,000 high-tech centrifuges mentioned by Abbasi. That would mean all would be in place by May 2014.

It was unclear how well the centrifuges would work, if and when they are started up. Iran has experienced persistent problems with its older machines.

The new IR-2ms are believed to be able to enrich two to five times faster than the old machines. For nations fearing that Iran may want to make nuclear arms, that would mean a quicker way of getting there.

The up-grade reflects Iranian resistance to attempts by six nations — the United States, Russia, China, Britain, France and Germany — which are trying to persuade Iran to curb its nuclear program. The latest Iran-six power talks ended April 6 without progress in Almaty, Kazakhstan. That extended years of inconclusive negotiations and increased fears that the diplomatic window on reaching a deal on Iran’s nuclear program may soon close.

Israel accuses Tehran of striving to make nuclear weapons and has threatened to bomb its atomic facilities to stop it from reaching that alleged goal if talks fail. The United States also has not ruled out such action as a last resort.

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